Mechanical Casing Spear Locking Mechanism for Hydraulic-Free Operation
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Solution Overview
Problem
Existing tubular handling equipment designs face issues with hydraulic power unavailability and accidental release due to incorrect rotational direction, lacking a mechanism to securely grip and lock tubulars without hydraulic operation and ensuring secure grip retention during rotation.
Innovation Solution
A surface handling tool employing mechanically operated slips and a lock that sets and locks with a common rotational movement, using a mandrel and lock segments that resist downward movement, ensuring the grip is not released by rotation, and allowing release only with axial movement when the tubular is supported on the rig floor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic power is used to operate locking mechanisms, then the locking function can be achieved, but the equipment cannot be deployed in locations where hydraulic power is unavailable
Solution Approach 1:
The patent replaces hydraulic power systems with a purely mechanical locking mechanism. The locking dog engages with notches on the mandrel through mechanical interaction, eliminating the need for hydraulic power while maintaining reliable locking functionality. This substitution enables deployment in locations without hydraulic infrastructure.
Solution Approach 2:
The mechanical locking mechanism is self-actuating through the rotation and axial movement of the mandrel itself. The locking dog automatically engages with the notches as the mandrel rotates and moves axially, without requiring external power sources or control systems. The structure serves its own locking function through its operational movements.
2Ease of operation
If slips are set with rotation, then the setting operation is simplified, but the grip may be accidentally released if rotation in the wrong direction is initiated
Solution Approach 1:
The locking dog and notches are designed with asymmetric geometry where the locking surfaces are configured to engage in one rotational direction but resist disengagement in the opposite direction. The locking dog has a inclined locking face that allows engagement during setting rotation but prevents release during reverse rotation, providing directional security.
Solution Approach 2:
The mechanical lock is pre-configured to prevent accidental release before it can occur. The locking dog engages with the notches to create a mechanical barrier that actively prevents the mandrel from rotating in the direction that would release the slips, countering the potential harmful effect of incorrect rotation before it can cause release.
3Adaptability or versatility
If a mechanical lock is used instead of hydraulic operation, then the equipment can operate without hydraulic power, but the mechanism complexity increases
Solution Approach 1:
The locking mechanism is divided into discrete functional components: the locking dog with its engagement surfaces, the notches on the mandrel, and the spring-loaded actuation system. This segmentation allows each component to perform its specific function efficiently while maintaining overall simplicity and ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tool securely grips and locks tubulars without hydraulic power, preventing accidental release during rotation and enabling controlled release when supported, ensuring reliable handling and retraction.
Implementation Method 1
The slips rub on the inside wall to hold an outer housing against rotation
Implementation Method 2
a spring compressed as the leading ramp of the top sub displaces the lock segments
Data Source
AI summary
A surface handling tool for casing employs slips to grab the casing internally and a lock that operates mechanically in conjunction with the setting of the slips. The slips rub on the inside wall to hold an outer housing against rotation. The top sub and mandrel are rotated in tandem relative to the outer housing that is held by the rubbing of the slips on insertion. The mandrel rises when rotated to extend the slips while lock segments ratchet over a series of protrusions that are shaped to resist downward movement of the mandrel. Once slips and lock are set, subsequent rotation will not release the lock or slips. When the casing is supported on the rig floor weight can be set down and a spring compressed as the leading ramp of the top sub retracts the lock segments such that rotation to the right can then retract the slips.